This evening I was helping a student with her work doing subtitles for a television program. She told me that they didn't give her a full script for the show and had two pieces of paper. One had blank spots indicated by stars and the other was a script of the narration, but not all of the dialogue between the narration. I assumed that the company had sent both documents and, as we went through it, I remarked that one bit of transcribing was badly done.
Later, as we continued and I saw the two different scripts, I realized my student had done the transcribing herself. That is, I had called her work "bad". When I realized this, I wanted to cringe because I didn't mean to insult her efforts. The dialog was fast and hard to understand and I don't blame her for having issues with it. I do blame a company whose business it is to offer the scripts for not giving her a better one. My comment was essentially saying that, "if this is the type of work they get paid to do, then they did a poor job." My student isn't paid to transcribe. She's paid to do the subtitles so her work was above and beyond and I so very much didn't meant to put down her work.
My husband had a similar experience in the past. He had a student who said she'd lie to her husband if it meant she wouldn't get hassled by him. He joked that he was glad he wasn't married to her in that case. She laughed, but he hasn't taught her since then. He meant not offense, but, in retrospect, it's possible that she took the joke poorly. He doesn't cringe about it though as he's a bit more easygoing than me.
These are the types of mistakes you sometimes make accidentally as a teacher which you would like to take back, but you really can't make up for it or apologize after the fact. Doing so just makes it worse by emphasizing the gaff. I'm sure I'm not the only teacher to unintentionally mess up like this. I'm also sure this won't be the last time I do this nor that I notice every time I do it.